In order to avoid ignition delays in the case of gas-discharge tubes, and particularly in the case of gas-discharge tubes used as over voltage arrestors, it is known in the art to have a radioactive material in the container in order to pre-ionize the gas filling. See German Pat. No. 615,506. It is also known to apply a ring-shaped tape of Nickel 63 on the inner surface of a tubular insulator member in the area between the electrodes, in order to pre-ionize the gas filling, which consists, for instance, of argon or helium. Krypton 85 has also been disclosed in the past for the pre-ionization. See Auslegeschrift No. 1,188,708.
It has also been suggested in the past to apply a radioactive fixed-member such as Promethium 147 on the tubular insulator member of over voltage arrestors, having magnesium oxide or glass solder as carrier substance.
The prior art gas-discharge tubes, and in particular, over voltage arrestors, which include a radioactive specimen for pre-ionizing the gas filling, have the drawback that the production cost of these tubes is relatively high. The extent of these costs is due to the safety measures when handling radioactive specimens, which are required, and the high price of these specimens. Furthermore, the prior art over voltage arrestors with radioactive specimens in their discharge chamber have the drawback that the electric function of these component elements is not always exact, due to the lack of reproducability of the fabrication system, and thus the reaction voltage.